Investigators say a fire that engulfed a party bus in downtown Vancouver on Saturday night was accidental but that the cause remains unclear. 

Around 10 p.m. PT the driver had dropped off some passengers along Granville Street when he smelled smoke and pulled over. 

The empty bus was parked with its engine running when it caught fire soon after. 

"The fire has been determined accidental (vs. malicious/suspicious). Any further cause determination will be done by their insurance company if they so choose," Jonathan Gormick of Vancouver Fire and Rescue Services wrote in an email to CBC.

The stunned driver called his boss as witnesses leaving nearby theatres began to gather. 

"He was panicking himself. When he called me the police and fire departments were there. I didn't understand at first what he was trying to tell me. Then when I heard him in a panic I realized something was serious," explained Silver Star Limo manager Amit Kang.

Police and 19 firefighters were needed to put out the flames but not before it gutted the party bus and also damaged a nearby tree and store awning. 

silver star limo vancouver party bus fire

The driver of this bus was in a panic after noticing smoke coming from the rear of the vehicle. Nobody was hurt in the fire on Granville Street Nov. 19. (Gian-Paolo Mendoza/CBC)

"They did have a challenge with shutting off the engine to the bus. It was left running. They had no way of shutting of the engine as the cab was burnt, so they had to manually just choke off the air filter," said Battalion Chief John Zacharuk, with Vancouver Fire Rescue Services.

Silver Star Limousines released a statement saying it was thankful there were no injuries. Staff said the company is insured and safety inspections were up to date.

"It still shocking. The main thing is everybody is safe," said Kang.

With files from Gian-Paolo Mendoza